Digestion in the stomach.

Functions of stomach 1. Digestive (mechanical treatment, absorption, evacuation, secretion, depo); 1. Digestive (mechanical treatment, absorption, evacuation, secretion, depo); 2. Excretor; 2. Excretor; 3. Incretor. 3. Incretor.

Secretor activity of stomach Production of stomach juice per day – near 2,5 L of juice. Their main components – enzymes, HCl and mucin. pH of morning saliva is neutral, after eating – sour – 0,8-1,5. Production of stomach juice per day – near 2,5 L of juice. Their main components – enzymes, HCl and mucin. pH of morning saliva is neutral, after eating – sour – 0,8-1,5.

Composition of stomach juice and their properties There are 2 types of glands – the oxyntic (or gastric) and the pyloric glands. The oxyntic glands secrete hydrochloric acid, pepsinogen, intrinsic factor, and mucus. The pyloric glands secrete mainly mucus. The main cells (peptic or chief cells) produce non active enzymes (pepsinogens). There are 7 pepsinogens. They hydrolyzed proteins. There are 2 types of glands – the oxyntic (or gastric) and the pyloric glands. The oxyntic glands secrete hydrochloric acid, pepsinogen, intrinsic factor, and mucus. The pyloric glands secrete mainly mucus. The main cells (peptic or chief cells) produce non active enzymes (pepsinogens). There are 7 pepsinogens. They hydrolyzed proteins.

Optimum pH of its activity is 1,5-2,0. Pepsinogens whose activity the most in the condition of pH 3,2- 3,5 is gastrecsin. In the stomach juice produces lipase and gelatinese. HCl produce in parietal or oxyntic cells. pH of it secrete is near 0,8. These processes need energy of lipids. Mechanism of it production: Cl - activly transported in the canaliculi, Na + – from the canal into cytoplasm. H 2 O dissopciated to H + and OH -. H + activly go into canaliculi in change of K +. In these processes take plase Na +,K + -ATPase. CO 2, which produce in cells act with H+ and syntheses HCO -. This anion go into the cell in change by Cl -. Optimum pH of its activity is 1,5-2,0. Pepsinogens whose activity the most in the condition of pH 3,2- 3,5 is gastrecsin. In the stomach juice produces lipase and gelatinese. HCl produce in parietal or oxyntic cells. pH of it secrete is near 0,8. These processes need energy of lipids. Mechanism of it production: Cl - activly transported in the canaliculi, Na + – from the canal into cytoplasm. H 2 O dissopciated to H + and OH -. H + activly go into canaliculi in change of K +. In these processes take plase Na +,K + -ATPase. CO 2, which produce in cells act with H+ and syntheses HCO -. This anion go into the cell in change by Cl -.

Formation of hydrochloric acid stomach Parietal cell blood metabolism se carboanhydrase

Role of the hydrochloric acid in the digestion 1. To promote the swell of protein; 1. To promote the swell of protein; 2. To promote the change of pepsinogen in pepsins; 2. To promote the change of pepsinogen in pepsins; 3. To make optimal conditions for actions of pepsins; 3. To make optimal conditions for actions of pepsins; 4. To fulfill protective role from bacteria; 4. To fulfill protective role from bacteria; 5. To promote motor and evacuated functions of stomach; 5. To promote motor and evacuated functions of stomach; 6. To stimulate production of duodinum gormon – secretin. 6. To stimulate production of duodinum gormon – secretin.

Phases of stomach secretion Cephalic phase is caused by nervous system. It has conditional and unconditional reflexes. Conditional reactions caused by appearance of food, it smell and other stimulus, which are connect with food. Unconditional influences is parasympathetic and beginning from receptors of tongue and other receptors of the oral cavity. From these receptors impulses pass through the fibers of n. trigeminus, n. facialis, n. glossopharyngeus, n. vagus to the medulla oblongata. Impulses return to stomach by n. vagus. Except neuron influences this phase has humoral influences – brunch of n. vagus produce gormon gastrin. These phase is very short. Cephalic phase is caused by nervous system. It has conditional and unconditional reflexes. Conditional reactions caused by appearance of food, it smell and other stimulus, which are connect with food. Unconditional influences is parasympathetic and beginning from receptors of tongue and other receptors of the oral cavity. From these receptors impulses pass through the fibers of n. trigeminus, n. facialis, n. glossopharyngeus, n. vagus to the medulla oblongata. Impulses return to stomach by n. vagus. Except neuron influences this phase has humoral influences – brunch of n. vagus produce gormon gastrin. These phase is very short.

Value of gastric juice secretion In norm gastric juice secretion must be NNNNNNNNIndexes Empty stomach Basal secretion Stimulated secretion 1.pH to 3,5 1,5-21,3-1,4 2. Production of common HCl, mmol/L Production of free HCl, mmol/L Debit of common HCl, mmol/hour to 1,5 1,5-5, Debit of free HCl, mmol/hour to ,5-12

Phases of stomach secretion Stomach phase is depends on the quantity of food, which are present in stomach. It has vago-vagal reflexes (by mean of central nerves system) and local – peripheral reflexes, which are closed in stomach walls. Duration of these phase is longer and quantity of juice is much. It has humoral mechanisms too (production of gastrin and histamin. Stomach phase is depends on the quantity of food, which are present in stomach. It has vago-vagal reflexes (by mean of central nerves system) and local – peripheral reflexes, which are closed in stomach walls. Duration of these phase is longer and quantity of juice is much. It has humoral mechanisms too (production of gastrin and histamin. Intestine phase: presence of food in the upper portion of small intestine can cause the stomach to secrete small amount of gastric juice. This probably results of gastrin are also released by the duodenal mucosa in response to distension or chemical stimuli of the same type as those that stimulate the stomach gastrin mechanism. Intestine phase: presence of food in the upper portion of small intestine can cause the stomach to secrete small amount of gastric juice. This probably results of gastrin are also released by the duodenal mucosa in response to distension or chemical stimuli of the same type as those that stimulate the stomach gastrin mechanism.